The present invention relates to a masonry block system for utilization as a retaining wall for retaining soil behind the wall.
The utilization of masonry fences as retaining walls is well known in the prior art; however, the significant pressures caused by the soil bearing upon the wall surface requires prior art masonry walls to incorporate a significant amount of steel in the form of re-enforcing bars extending through the voids in the masonry block into a footer. A variety of techniques have been used in the prior art in an attempt to strengthen the wall and to provide sufficient resistance to the pressure caused by soil pressing against one side of the wall; these techniques are usually complicated and always expensive. Some prior art techniques have incorporated post-tensioning wherein courses of block have been compressed with respect to each other and the compressed courses are then secured in some manner to a foundation. These latter techniques usually require expensive installation provisions for appropriately supporting the compressed courses on the designated footer.
It is therefore an object of the present invention to provide a masonry retaining wall system that may be constructed relatively inexpensively and nevertheless retain strength to resist the forces of the soil pressing against one side thereof.
It is another object of the present invention to provide a retaining wall system wherein a very high strength wall is provided for retaining soil and which provides a base upon which a less expensive extending wall may be supported thereon.
It is still another object of the present invention to provide a retaining wall system that can be inexpensively constructed while providing all of the advantages of a retaining wall system while still providing an economical means for supporting a fence extending beyond the grade level of the soil being retained by the retaining wall.
It is still another object of the present invention to provide a method for constructing a retaining wall system.
It is still another object of the present invention to provide a retaining wall system incorporating post-tensioning wherein the courses of block within the retaining wall are compressed against the footer or foundation to provide a significant cost reduction in the construction of the retaining wall.
The present invention incorporates a masonry retaining wall structure that utilizes a footer for supporting a retaining wall""s first course of masonry block to be positioned at the grade level of the lower grade of retaining wall system. Post-tensioning rods are imbedded in the footer concrete and incorporate an upset end and a flange member secured to the post-tensioning rod; the post-tensioning rod is angled upwardly and extended vertically from the footer. A plurality of courses of masonry block are then placed on the footer with the respective post-tensioning rods extending through the voids therein. The blocks are positioned with the post-tensioning rods closer to the side of the blocks contacted by the soil.
The post-tensioning rods extend upwardly beyond the top course of the masonry block. A plurality of bridging clamping plates extend across the voids of selected masonry blocks in the top course of blocks, each of the plates having an opening therein to permit the passage of an end of a respective post-tensioning rod. The end of the post-tensioning rod is threaded to accept a nut which is then placed on the rod and threaded to engage the clamping plate. Predetermined tension is then placed on the respective post-tensioning rods.
A cap course of blocks may be placed over the top course of masonry blocks to act as a protection for the threaded ends of the post-tensioning rods and the plates and nuts placed thereon.
This cap course may also form the foundation of a masonry wall, or fence, that extends above the retaining wall and above the grade level of the upper grade of the retaining wall system. The extending masonry fence may be constructed using conventional techniques with selected reinforcing bars extending through the retaining wall masonry blocks into the wall footer; alternatively, the extending fence may be constructed using post-tensioning techniques described and claimed in U.S. Pat. No. 4,726,567.